1. Field of the Invention
This invention involves a means of constructing a foundation and floor which provides improvement over existing practices.
2. Prior Art
Foundation construction practices share common challenges world wide. Relative to the requirements of a structure, a building site must be considered a random surface. This randomness must be interrelated to an orthogonal grid upon which the remainder of the structure is referenced and built to. Thus, building a foundation involves a process, such as building forms for in situ concrete, requiring the locating of many points in three dimensional space. A random earth surface serves as the basis for any structure required to remain at these points. Work involving the measuring must be done carefully. Skilled, and therefore expensive labor is essential. Irregular terrain or mucky ground surface slows progress of work. Bad weather may stop it altogether.
A concrete foundation requires that forms be built and secured so that they will not dislocate as concrete, weighing 140 pounds per cubic foot, is placed into them. Part of the foundation construction may also be sculpting the earth surface to conform to the building grid, such as would be done for a concrete slab on grade. However, user requirements, site conditions or equipment costs often dictate the use of foundation walls with a raised floor in lieu of, or in conjunction with, any slab on grade.
Conventionally, concrete is placed before any structure which is to be above it. Commonly the foundation is built by a different party than those building the superimposed structure. Thus the foundation crew has less motivation to be careful with time consuming checks, such as squareness of corners, than the subsequent construction crews would like. Once concrete has set, it is very difficult to fix any dimensional errors or misplaced hardware. Skilled labor is consumed in measuring an as-built foundation. Labor and management time is subsequently consumed in dealing with any error. Even with the best of intentions, a foundation may turn out to be inaccurate due to miserable site conditions. It is difficult work.
Some construction materials recently gaining acceptance, such as steel stud framing, are much less accommodating of normal surface irregularities in concrete than wood framing is. Because of this, many hours of labor are spent fussing with cuts of metal studs that frame to the top of a foundation wall.
In custom foundation construction, many hours are spent on such things as: Building multiple batter structures to secure guide strings; attempting to re-square sets of those strings while they quiver in the wind, with that squaring process depending upon floating points of intersection; or adjusting superimposed structural framing to suit an inaccurately built foundation. There are many time consuming problems in foundation construction, and the potential for improvement is enormous.
An object of this invention is to build a higher quality foundation for less cost than conventional methods allow.
This new means of construction quickly secures permanent structural members accurately into position before any concrete is placed. The resulting structural assembly also supports any concrete forms. Walls are physically defined, automatically, according to the layout of a user directed computer aided drawing.
This means of constructing a foundation allows inexpensive, one dimensional computer aided manufacturing technology to replace field labor. It utilizes standard sections of cold formed gage steel, with distribution currently established and improving, to replace a diminishing supply of wood members, as they are commonly used. This set of metal members, of standard and custom lengths, make up a kit which is self squaring as it is rapidly assembled to exactly the right dimensions and at the proper elevation.
This means constructs a foundation which has a floor of metal joists, or of a concrete slab on grade. Subsequently placed walls may be of any material. Defining elements of walls may be secured in place and cast with in situ concrete.
Reasons for a building contractor to utilize this method of building a custom foundation include the following:
A) Save significantly on field labor costs PA1 B) Save on site grading costs PA1 C) Save on labor attaching superimposed wall framing PA1 D) Reduce Contractor's inventory costs PA1 E) Build a higher quality foundation PA1 F) Appropriate range of adaptation PA1 G) Easy availability PA1 H) Rapid completion PA1 I) Suits low income housing projects PA1 J) Suits prefabricated projects PA1 K) Consistent reliability of performance
1) Less labor required PA2 2) Less skill required PA2 1) Building pad creation or compaction not required PA2 2) Infringe code required crawl space clearances for wood PA2 1) Designed specifically to accept metal framed walls PA2 2) Designed specifically for walls of concrete material PA2 3) Any other wall material may be used as well PA2 1) Metal foundation wall forms are used as floor joists PA2 2) Standardized, durable, low cost, interchangeable parts PA2 1) More accurate and consistent PA2 2) No vegetable matter to decay PA2 3) Attractive surface pattern on concrete walls PA2 1) Variation of site PA2 2) User requirements PA2 1) Distribution established by AISI member manufacturers (American Iron and Steel Institute) PA2 1) Allows tight schedules PA2 2) Fits narrow weather windows
a) Set into place without any fuss PA3 b) Cast into place parts as desired
Labor is saved initially due to the fact that this method avoids the need to set up batterboard structures and strings to define foundation edges. Only one string need be set. The previously required, lower accuracy layout for footings may be done by any method, such as tape measuring and marking earth immediately before a backhoe cuts any trench.
Labor is further saved by the fact that no field cutting of horizontal members is required. Prepunched holes in members of controlled lengths, combined with snap in connections, facilitate rapid assembly of a self squaring structure. These lengths may be modular or special, as determined by the software that also determines CNC output, piece marking, and packaging.
No fitting of structural elements to irregular, hardened concrete is ever necessary. Members may be cast in situ, or a new tool may be used to work a flat, accurate concrete surface within tolerance required of metal studs. Anchor bolts are not required, nor is the time consuming process of locating penetrations in a sill framing member for those bolts.
Since cost of a joisted floor is thereby lowered, many projects will save in using this over a slab on grade, because of equipment costs involved in preparing a site for those slabs. The typical home owner prefers a joisted floor because of the cushioning spring action, and because underfloor electrical, plumbing, or mechanical modifications are possible. The building contractor likes being able to sell the wall forms to the job as floor joists.
An insulated decking over metal joists, which combines with a radiant heat floor slab, is a standard deployment of this construction. This avoids the need to install underfloor insulation. It also avoids any need for a plywood type product which has potential to rot.
All parts for this structural system are inexpensive. Interchangability is maximized. After concrete placement, foundation wall form members simply unsnap from the wall face and connect into girders at prelocated, prepunched holes. Lengths of these members need not be adjusted for this switch from form to joist, even at end bays of a custom length. The same holes find mating elements for either use. The software does all the hard work.
The cold formed joist members have a far higher standard of quality control and straightness than does wood. The metal forms fare much better than wood if they are required for multiple form uses. The standard edge radius of these stacked members produces an attractive pattern on the concrete surface. Any surface effects at form connection locations are hardly noticeable.
Since no vegetable material is required in this construction, concerns about rot and termites are not required either. Crawl spaces may be shallower than codes require for wood. Crawl space vents, which can lose precious heat in the winter, may be minimized or omitted, because building codes require crawl space ventilation specifically to avoid rot in wood members.
Any reasonable building site is appropriate for this means of construction. The main floor elevation may be well above or below exterior grade. Any horizontal dimension may be met. Vertical dimensions between steps in floor height are in small modules. Stemwall height may be at any such relative modular increment, below, at, or above floor framing. Retaining walls may be integral with this assembly.
Since a level working platform may be erected quickly, other aspects of construction are facilitated sooner. The critical period of a foundation site being cut open and most vulnerable to weather is minimized. Concrete can be placed the same day trenches are dug.
By use of this invention, a better foundation and floor structure may be built at a lower cost than is possible with current practices for custom buildings.